Esters of dialkylallyl alcohols

ABSTRACT

ESTERS OF DIALKYLALLLYL ALCOOHOLS CHARACTERIZED BY THE STRUCTURAL FORMULA   R1-CH2-CH=C(-R2)-CH2-O-CO-R3   WHEREIN R1 AND R2 EACH REPRESENT A LOWER ALKYL, AND R3 REPRESENTS HYDROGEN, A LOWER ALKYL OR LOWER ALKENYL OF FROM 1 TO 8 CARBON ATOMS, ARYL, ARALKYL OR ARYLALKENYL ARE PREPARED BY SELECTIVE REDUCTION OF SUITABLE ACROLEINS FOLLOWED BY ESTERIFICATION. THE COMPOUNDS HAVE VERY PLEASANT, STRONG AND LONG LASTING AROMAS AND ARE USEFUL AS COMPOUNDS IN FRAGRANCE COMPOSITIONS.

United States Patent ice 3,832,369 ESTERS 0F DIALKYLALLYL ALCOHGLS Alfred A. Schleppnik, St. Louis, Mo., and John B. Wilson, Old Bridge, N.J., assignors to Monsanto Company, St. Louis, M0. N0 Drawing. Filed Jan. 14, 1972, Ser. No. 217,957 Int. Cl. C070 69/14, 69/24; Cllb 9/00 U.S. Cl. 260-410.9 N 4 Claims ABSTRACT OF THE DISCLOSURE Esters of dialkylallyl alcohols characterized by the structural formula wherein R and R each represent a lower alkyl, and R represents hydrogen, a lower alkyl or lower alkenyl of from 1 to 8 carbon atoms, 'aryl, aralkyl or arylalkenyl are prepared by selective reduction of suitable acroleins followed by esterification. The compounds have very pleasant, strong and long lasting aromas and are useful as compounds in fragrance compositions.

This invention relates to the art of fragrance compositions and, more particularly, to a novel class of compounds possessing a characteristic aroma. More specifically, this invention is directed to a novel class of useful compounds, their preparation and use of such compounds as fragrances.

The art of perfumery began, perhaps, in the ancient cave dwellings of prehistoric man. From its inception, and until comparatively recently, the perfumer has utilized natural perfume chemicals of animal and vegetable origin. Thus, natural perfume chemicals such as the essential oils, for example, oil of rose and oil of cloves, and animal secretions such as musk, have been manipulated by the perfnmer to achieve a variety of fragrances. In more recent years, however, research perfume chemists have developed a large number of synthetic odoriferous chemicals possessing aroma characteristics particularly desired in the art. These synthetic aroma chemicals have added a new dimension to the ancient art of the perfumer, since the compounds prepared are usually of a stable chemical nature, are inexpensive as compared with the natural perfume chemicals and lend themselves more easily to manipulation than natural perfume chemicals since such natural perfume chemicals are usually a complex mixture of substances which defy chemical analysis. In contrast thereto, the synthetic aroma chemicals possess a known chemical structure and may therefore be manipulated by the perfumer to suit specific needs. Accordingly, there is a great need in the art of fragrance compositions for new compounds possessing specific characteristic aromas.

The principal object of the present invention is to provide a new class of aroma chemicals consisting of esters of dialkylallyl alcohols.

Another object of the present invention is to provide a specific class of compounds having a characteristic aroma which are useful in the preparation of fragrances and fragrance compositions.

These and other objects, aspects and advantages of this invention will become apparent from a consideration of the accompanying specification and claims.

In accordance with the above objects, there is provided by the present invention a novel class of compounds characterized by the structural formula wherein R and R each represent a lower alkyl of from 1 to 8 carbon atoms, and R represents hydrogen, a lower 3,8323% Patented Aug. 27, 1974 alkyl or lower alkenyl of from 1 to 8 carbon atoms, aryl, aralkyl or arylalkenyl.

The compounds of this invention have very pleasant, strong and long lasting aromas and are useful as compounds in fragrance compositions.

Representative lower alkyls characterized by R R and R in the above formula include methyl, ethyl, npropyl, i-propyl, n-butyl, i-butyl, terz-butyl, n-amyl, iamyl, tert-amyl, n-octyl and the like.

The precusors of novel compounds of this invention are prepared by selective reduction of the acroleins characterized by the structural formula wherein R and R have the same meaning as defined hereinabove, to the corresponding alcohols which are then esterified in a known manner with organic acids characterized by the structural formula wherein R has the same meaning as defined hereinabove.

The acroleins described above include compounds such as Z-methylpent-Z-en-l-al, 2-n-butyloct-2-en-l-al, 2- n amylnon-Z-en-l-al, 2-n-propyl-hept-2-en-l-al, and the like.

The organic acids described above include compounds such as formic acid, acetic acid, propionic acid, benzoic acid, caprylic acid, phenylacetic acid, cinnamic acid and the like.

The novel compounds of this invention are useful in the preparation and formulation of fragrance compositions such as perfumes and perfumed products due to their pleasing, strong and long lasting aroma. Perfume compositions and the use thereof in cosmetic, detergent and bar soap formulations and the like are exemplary of the utility thereof.

The compounds of this invention are used in concentrations of from trace amounts up to about 50 percent of the perfume composition into which they are incorporated. As will be expected, the concentration will vary depending on the particular fragrance composition and even within the same composition when compounded by different perfumers.

The following examples will serve to illustrate certain specific embodiments within the scope of this invention and are not to be construed as limiting the scope thereof.

EXAMPLE 1 2-n-propyl-hept-2-enl-ol To a solution of 3.0 grams of lithium aluminum hydride in 200 ml. anhydrous ether was added, with stirring, a solution of 46.26 grams of 2-n-propyl-hept-2-en-l-al in 50 ml. ether at such a rate that the ether continually refluxed gently. After the addition was completed the mixture was heated to reflux for 20 minutes. GLC analysis then indicated that a small portion of the aldehyde has remained unchanged. To the reaction mass was added 0.3 grams of lithium aluminum hydride and refluxing was continued for 10 minutes after which time all of the aldehyde was consumed. Excess lithium aluminum hydride was removed with ethyl acetate. Water and HCI were added to wash the reaction product and the reaction mass was subject to distillation at 40 ml. at C. 47.17 grams of a colorless liquid was obtained. Boiling point 87 C./3.4 mm. Hg n =l.4559. The material was submitted to a fragrance panel for aroma characterization and it was described as having waxy, butyric and nutty aromas.

3 EXAMPLE 2 2-n-propyl-2-heptenyl acetate To a solution of 30.6 grams of acetic anhydride and 8.0 grams of pyridine, 15.6 grams of 2-n-propyl-hept-2- en-ol were added slowly. The resulting solution was maintained at room temperature for 15 hours. The solution was then poured into 250 ml. of ice and stirred occasionally until all the excess acetic anhydride had been hydrolyzed. A two phase system was formed which was extracted twice with 100 ml. of ether, an eighth solution was washed once with 100 ml. of a saturated sodium bicarbonate solution followed by washing twice with 100 ml. of water with subsequent drying over sodium sulfate. The dried ether solution was filtered and concentrated in a Rinco evaporator. The reaction product was distilled through a short Vigreaux column at 105 C. and 10 mm. Hg to yield 16.9 grams of product having an n =1.4399. The material was submitted to a fragrance panel for aroma characterization and it was described as having green, cut stem and apple aromas.

EXAMPLE 3 Z-n-propyl-Z-heptenyl propionate To a /2 liter, 3-necked flask was added 46.8 grams (0.3 moles) of 2-n-propyl-hept-2-en-l-ol, 31.2 rams (0.4 moles) of propionic acid and 0.1 grams of p-toluene sulfonic acid and 100 ml. of benzene. The resulting reaction mixture was refluxed and water was continuously removed by a Dean-Stark trap D-S. After 4 hours of refluxing, 5.4 ml. (0.3 moles) of water were collected and the reaction mass was allowed to cool. The resulting mixture was extracted three time with saturated sodium bicarbonate solution to remove any excess acid and was then washed once with a saturated sodium chloride solution. The benzene was then removed by a Rinco evaporator using vacuum at 98 C. and 3 mm. of mercury and 50.90 grams were recovered. The distilled product contained an acid overtone which was unacceptable so the product was redistilled under vacuum at 0.1 mm. of mercury through a warm meter packed column with a thermal watch and 85 reflux. This yielded 31.11 grams of product which had an 11 of 1.4407. The material was submitted to a fragrance panel for aroma characterization and it was described as having light woody, greeny and fruity aromas.

EXAMPLE 4 2-n-propyl-2-heptenyl caprylate To a half liter, 3-necked flask equipped with a stirring assembly, reflux condensor and Dean-Stark trap, was added 31.2 grams (0.20 moles) of 2-n-propyl-hept-2-en- 1-ol, 36.0 grams (0.25 moles) of caprylic acid and 0.1 grams of p-toluene sulfonic acid in 100 ml. of benzene. The reaction mixture was refluxed for 19 hours at which time 7.2 grams (0.05 moles) of caprylic acid were added to complete the reaction. Refluxing was continued until a total of 23% hours had elapsed and 7.2 grams (0.05 moles) of caprylic acid were added and 30 ml. of benzene were removed from the reaction mixture. The reflux temperature was raised from 85 C. to 110 C. The reaction mass was extracted four times to remove the excess acid. Two phases formed and the organic layer was placed in a Rinco evaporator and the benzene was removed yielding 67.4 grams of crude product. The product was distilled under vacuum at 123 C. and 0.55 ml. mercury yielding 24.68 grams of the product which has an 11 =1.4490. The material was submitted to a fragrance panel for aroma characterization and it was described as having green, woody and waxy aromas.

EXAMPLE 2-n-propyl-2-hepteny1 phenylacetate Following a procedure similar to Example 4, but using phenylacetic acid in place of the caprylic acid resulted in 4 the formation of 2-n-propyl-2-heptenyl phenylacctate which had an rz =1.4920. The material was submitted to a fragrance panel for aroma characterization and it was described as having sweet, honey, greenish and floral aromas.

EXAMPLE 6 Z-n-propyl-Z-heptenyl cinnamate Following a procedure similar to Example 4, but utilizing cinnamic acid in place of the caprylic acid resulted in the formation of 2-n-propyl-2-heptenyl cinnamate which had a melting point of 133 to 134 C. The material was submitted to a fragrance panel from aroma characterization and it was described as having waxy, sweet, almond and spicy aromas.

EXAMPLE 7 2-n-propyl-2-heptenyl benzoate Following a procedure similar to Example 4 but utilizing benzoic acid in place of the caprylic acid resulted in the formation of 2-n-propyl-2-heptenyl benzoate. The

material was submitted to a fragrance panel for aroma characterization and it was described as having green, waxy and floral aromas.

EXAMPLE 8 2-ethyl-hex-2-en-1-ol To a 1 liter, S-necked flask equipped with a dropping funnel, stirring assembly and reflux condenser was added 4.94 grams (0.13 moles) of lithium aluminum hydride in 300 ml. of ether via the dropping funnel. To this mass was added 63.0 grams (0.5 moles) of 2-ethyl-hex-2-en-1- al in 100 ml. of ethylether over a period of time so as not to overload the condenser with ether. After the addition had been completed the mixture was stirred for 1 hour. At this time 4.4 grams (0.05 moles) of ethyl acetate was added to destroy any excess lithium aluminum hydride. The mixture was allowed to react for another hour and then ml. of H 0 were added together with vigorous stirring for 5 minutes. The ether phase was decanted off and the precipitate was dissolved in dilute aqueous hydrochloric acid. The acid solution was extracted twice with 50 ml. of ether. The ether solutions were combined and concentrated at one atmosphere until the pot temperature reached 50 C. The mixture was distilled twice at reduced pressure (54 C./2.0 ml. of mercury). First distillation yielded 5 fractions and the second which was a combination of the first four cuts of the first distillation yielded four fractions. Fractions 5-1 and 4-2 were combined resulting in 27.3 grams of the product which had an n =1.4491. The material was submitted to a fragrance panel for aroma characterization and it was described as having green, woody, vetiver/patchouly and sweet aromas.

EXAMPLE 9 2-ethyl-2-hexenyl acetate Following a procedure similar to Example 2 but utilizing Z-ethyl-hex-Z-en-l-ol in place of 2-n-propyl-hept-2-enl-ol resulted in the formation of 2-ethyl-2-hexenyl acetate which had an n =1.4353. The material was submitted to a fragrance panel for aroma characterization and it was described as having green, floral and woody aromas.

EXAMPLE 10 2-ethyl-2-hexenyl formate 23.1 grams (0.487 mole) of 97 percent formic acid was added to 49.4 grams (0.484 mole) of acetic anhydride over 7 minutes while holding the reaction temperature at 4550 C. and the mixture was stirred an additional hour. Then 56.3 grams (0.439 mole) of 2-ethylhex-2-en-1-ol, containing 5 percent of the saturated alcohol and 8 percent of an unidentified impurity, was added over 56 minutes while holding the temperature at 45-50 C. After one hour additional stirring there was 1.4 percent unreacted alcohol left. The reaction mixture was diluted with 50 ml. of benzene and washed in a separation funnel at 35-40 C. with 100 ml. portions of water (three times), saturated bicarbonate, water and brine. The organic layer Was refluxed two hours with 0.32 grams of boric acid. Distillation of the reaction mixture gave the main fraction boiling 942-1000 C./331 mm. of Hg, having a n =1.4363. The material was submitted to a fragance panel for aroma characterization and it was described as having woody, fresh, green, spicy, floral and caraway seed aromas.

While this invention has been described hereinabove with regard to certain illustrative specific embodiments, it is not so limited since many modifications and variatrons are possible in the light of the above teachings. It is understood therefore that the invention may be prac- 1 ticed otherwise than as specifically described without de- 5 3. 2-n-propyl-2-heptenyl caprylate. 4. 2-ethyl-2-hexenyl formate.

References Cited UNITED STATES PATENTS 3,079,429 2/ 1963 Chafetz 260-494 3,284,517 11/1966 Rylander et a1. 260-638 2,995,600 8/1961 Webb 260-488 2,921,089 1/1960 Hagemeyer et al. 260-475 OTHER REFERENCES Chemical Abstracts, vol. 29, 4504-51 (1935). Chemical Abstracts, vol. 54, 13780 (1960). Chemical Abstracts, vol. 62, 16036a (1965).

LEWIS GOTTS, Primary Examiner n. G. RlVERS, Assistant Examiner U.S. Cl. X.R.

260-476 R, 486 R, 488 H, 638 B, 654 R; 252-522 

